Solid state auxiliary controllers



May 21, 1968 J. v. SELZER ETAL SOLID STATE AUXILIARY CONTROLLERS 2Sheets-Sheet 1 mm amk 200 ET i un w IODOmIk moZwEQ m a 1) 8 DETECTORMEMORY RELAY 42 y 1968 J. v. SELZER ETAL 3,384,871

SOLID STATE AUXILIARY CONTROLLERS Filed Oct. 22, 1965 2 Sheets-Sheet 2T0 UNIJUNCTION TRANSISTOR Q3 l2v no REMOTE FLASH United States Patent3,384,871 SOLID STATE AUXILIARY CONTROLLERS John V. Selzer, 410 LindenBlvd. 11203, and Philip Cane, 697 E. 22nd St. 11215, both of Brooklyn,N.Y. Filed Oct. 22, 1965, Ser. No. 502,248 14 laims. (Cl. 340-41) Thepresent invention relates in general to apparatus and techniques forresponding to an abnormal condition in a system, such as a signallingsystem for controlling the flow of traffic across an intersection, andmore particularly concerns novel semiconductor circuitry arranged toreliably respond to an abnormal condition by activating a cautioningsignal so as to allow the, fiow of traflic across the intersection whilewarning operators of vehicles to exercise appropriate caution beforeentering the intersection.

One problem with traflic signals that control the flow of traflic acrossan intersection is that the controller may fail and direct traflic alongone direction to go and traffic along an intersecting direction to stopfor an abnormally long period of time. This type of failure frequentlyresults in operators signaled to stop moving across the intersection indisregard of the signal while a vehicle approaching from the directionsignaled to go may proceed into the intersection without realizing thefailure of the signal. The dangers involved are apparent.

It is possible to prevent this unsafe condition from developing byemploying a relay system that automatically signals trafiic approachingthe intersection from all directions to exercise caution upon detectingthis condition of failure. While this system is very effective, it has anumber of disadvantages. Typically at least some of the relays in thesystem must switch each time a traflic signal light changes color. Thislarge number of switchings may result in deterioration in the relayelements so that when a failure does occur, the relay elements might notbe in a condition to effect the desired changeover to a cautioningsignal.

Accordingly, it is an important object of this invention to provide areliable system for responding to the failure of a traflic controllerwhich ceases to function for reasons other than power failure.

It is another object to achieve the preceding object with relativelyfew, but reliably operating, semiconductor devices.

It is still another object of the invention to achieve the precedingobject with apparatus suitable for use both with controllers in whichtraflic flow along the different intersecting directions is sequencedentirely on a time basis and controllers in which the flow may also beassigned on a demand basis.

It is still another object of the invention to achieve the precedingobjects with apparatus that also allows the cautioning signal source tobe activated by independent means.

According to this invention, there is a source of a cautioning signal,such as a flashing yellow light. An output semiconductor device has afirst or normal state which normally is ineffective for exciting thecautioning signal and a second or abnormal state which activates thecautioning signal source to produce the cautioning signal, such as theflashing of the yellow light. A first semiconductor device timingcircuit responds to a first set of control signals, such as the signalsdirecting the flow of traffic along a first direction, and a secondsemiconductor device timing circuit responds to a second set of signals,such as the traflic control signals directing trafiic along a seconddirection, to provide normal signals to the output semiconductor devicethat maintains the latter in its first state. When either semiconductordevice timing circuit ice senses an abnormal sequence of controlsignals, that circuit provides a signal causing the output semiconductordevice to assume the second state and activate the source of acautioning signal.

According to another feature of the invention input coupling means mayalso be provided from a first phase input terminal to the firstsemiconductor device timing circuit and from a second phase inputterminal to the second semiconductor device timing circuit to allow theapparatus to also respond to signals that might be provided by memoryrelay or relays in a demand controller Where trafllc is signaled to goonly when a vehicle approaches the intersection from either of the crossstreets.

Numerous other features, objects and advantages of the invention willbecome apparent from the following specification when read in connectionwith the accompanying drawing, in which:

FIG. 1 shows essentially a schematic circuit diagram of an embodiment ofthe invention; and

FIG. 2 shows a modification of FIG. 1 that achieves essentially theperformance of the circuit of FIG. 1 with fewer components.

With reference now to the drawing and more particularly FIG. 1 thereof,there is shown a schematic circuit diagram of a preferred embodiment ofthe invention in which a flash relay 11 is energized when relay K1 isenergized in response to an abnormal condition to flash the amber lights13 and red lights 14 along the through street direction 16 and crossstreet direction 15, respectively. Typically this abnormal condition issensed when either the power to the cross street green light 17 or tothe through street green light 18 remains off for longer than apredetermined time interval determined by semiconductor device timingcircuits 21 and 22. The power to the lights is provided by aconventional controller with contacts illustrated in FIG. 1 but notfurther described because such controllers are well known in the art.

The apparatus includes a power supply preferably arranged to convertconventional volt A-C power into 24 volts across the secondary oftransformer 23 and provide potentials for energizing various points. Theterminals designated i receive 110 volt A-C. The terminals designated Eare at 24 volts A-C. The terminals designated E receive a half-waverectified DC potential provided through diode D12. The terminalsdesignated E receive a filtered positive D-C potential provided throughdiode D13. The terminals designated E receive a filtered negativepotential provided through diode D14.

Flash relay 11 may be actuated with relay K1 in its normally deenergizedposition by an external flash signal provided by flasher control signalsource 24 when it is desired to normally flash the lights 13 and 14, forexample, during early morning hours when traflic is light.

The normal condition is maintained when a green light, such as throughgreen light 18 is energized to provide a train of half-wave rectifiedpulses through diode D2 that pulses NPN transistor Q1 to dischargecapacitor C1 and prevent it from being charged through diode D7 andtiming potentiometer 26 above a critical potential correspondingessentially to the firing potential of the emitter of output unijunctiontransistor Q3. This critical firing potential is sufficient to allowcapacitor C1 to discharge through diode D9 and render unijunction outputtransistor Q3 momentarily conductive. Output transistor Q3 draws enoughcurrent through relay K1 to operate the relay. Holding contacts 20 thenkeep relay K1 in the operate condition until release button 25 ispressed. Thus, so long as power is fed to through green light 18,transistor Q1 conducts to prevent capacitor C1 from being chargedsufliciently to render unijunction transistor Q3 conductive. Similarlycapacitor C2 is charged through means including diode D8 unlesstransistor Q2 is rendered conductive by an impulse transmitted throughdiode D5 when cross street green light 17 is supplied with voltage.Thus, if cross street light 17 remains inactive for too long aninterval, capacitor C2 charges to a potential sufficient to renderunijunction transistor Q3 conductive. On the other hand, if throughstreet green light 18 remains inactive for an excessive interval,capacitor C1 charges to a potential sufficiently high to renderunijunction output transistor Q3 conductive. When unijunction transistorQ3 conducts momentarily, relay K1 is energized to initiate flash relay11 and close holding contacts 20 until such time as release button ispressed.

A unijunction transistor, or double-base diode, comprises a singlerectifying contact the emitter, situated approximately midway along asemiconductor bar which carries two ohmic base contacts at its ends.Appropriately biasing the bar with a potential across the base contactsestablishes a negative resistance characteristic between the emitter anda base. This characteristic is between the emitter and base connected torelay K1 in the preferred embodiment.

The circuit techniques according to the present invention employingpulses derived from the ordinary power line have a number of advantages.Power consumption is relatively low. Relatively low power semiconductordevices may be employed. Yet, positive desired switching occurs incircuitry that is relatively insensitive to noise. And the power supplycircuitry is relatively simple and inexpensive.

The rate at which capacitors C1 and C2 charge may be controlled by thevalues of ganged potentiometers 26 and 27 so that the limit period maybe established well, in excess of the normal green duration for eithercross or through trafiic. The charging time constant is preferably muchgreater than the discharge time constant of the path through aconducting transistor Q1 or Q2.

The apparatus also includes a remote flash inhibitng channel forpreventing the timing circuits 21 and 22 from indicating a failure whenthe controlled flash condition has been selected by flash signal source24. Sourse 24 provides signals through diodes D3 and D4 to periodicallyrender transistors Q1 and Q2, respectively conductive so that capacitorsC1 and C2 remain essentially in the discharged state and K1 cannot beenergized.

Still another feature of the invention resides in having the apparatusadaptable for a vehicle actuated controller in which through streetlights 16 remain green until a vehicle is ready to enter theintersection from a cross street. by connecting the phase B detectorline to the detector device in the traffic signal controller, which maybe a memory relay 31 that remains deenergized until the vehicle actuatesswitch contacts 32, a 12 volt A-C signal may pass through relay 31through means including diode D6 to inhibit the charging of capacitor C2by periodically rendering transistor Q2 conductive. At the same time,transistor Q1 is rendered periodically conductive by the green signaltransmitted through diode D2 to keep capacitor C1 from chargingappreciably. A phase A detector line is also provided for transmitting asimilar signal through diode D1 should it be desired to maintain thecross street direction in the normally green condition. When switch 32is closed, relay 31 is energized to effectively connect the 12 volt A-Cground and prevent transistor Q2 from being rendered conductive.Consequently, capacitor C2 may be charged should the cross street light17 not return to the green condition for too long a period.

Referring to FIG. 2, there is shown a schematic circuit diagram ofalternate circuitry according to the inven tion in which the number ofmonitored signals are reduced. Since the circuitry to the right ofdiodes D9 and D10 is identical to that in FIG. 1, FIG. 2 shows only themodified circuit portions to the left of the latter two diodes.Corresponding elements in F168. l and 2 are identified by the samereference symbol. Having described the circuit arangement of FIG. 1,FIG. 2 is best described by explaining what changes have been made inthe circuit of FIG. 1 to produce the circuit of FIG. 2.

The ganged potentiometer resistance 27 has been eliminated so thattiming adjustment is controlled entirely by adjusting potentiometer 26.The line leading from the B detector through diode D6 is eliminated andno signal from the G2 terminal need be delivered through diode D5 to thebase of transistor Q2. Instead a capacitor 41 is connected acrossresistor R10 from the base of transistor Q2 to a source of positivedirect potential such as E1. Diode D5 is connected poled as shownbetween the base of transistor Q2 and the anode of diode D2 whichjunction then receives a signal representative of the selection of amberfor one of the directions. The B detector signail is coupled throughdiode D1 to the base of transistor Q1.

Operation is as follows. Capacitor C1 again charges through timingpotentiometer 26 at a rate determined by the adjustment of the latter.When. the controller designates by signal A1 that a corresponding amberlight be ignited, diode D2 provides a rectified signal that rendersnormally nonconductive transistor Q1 conductive to discharge capacitorC1.

Transistor Q2 performs the function of sensing failure whereby thecontroller continuously provides a control signal A1 for continuousselection of an amber light. This fault is recognized when diode D5provides a rectified signal across capacitor 41 to render transistor Q2,now normally conductive in the circuit of FIG. 2 nonconductive so thatcapacitor C2 can charge to a potential suflicient to render unijunctiontransistor Q3 conductive.

The time constant of resistor R12 and capacitor C2 is chosen to besufliciently large so that the potential on capacitor C2 cannot rise toa value sufiicient to render diode D10 conductive for the normalduration of an amber signal.

The circuitry of FIG. 2 is also suitable for use with semi trafficactuated equipment. With such equipment the controller may stay in thegreen one (C1) position indefinitely. The memory relay 42 in thecontroller equipment then couples a 12 volt A-C signal representative ofthe B detector state through diode D1 to render transistor Q1 conductiveand keep capacitor C1 discharged. If a vehicle approaching from thecross street calls for a green two (G2) signal to turn the cross streetgreen light green, relay 42 is energized to close the associatedcontacts and place the B line essentially at ground potential toestablish a negative potential on transistor Q1 rendering thattransistor nonconductive. If the cross street green light remains greenfor too long, capacitor C1 charges to a sufficiently high potential torender unijunction transistor Q3 conductive.

As in the circuit of FIG. 1, conducting unijunction transistor Q3 pullsin reay K1. Relay K1 locks through its own holding contacts 20 and therelease push button 25. Other contacts of relay K1 also operate theflash relay 11 that is responsible for turning the signal lights into aflashing condition.

In a manner similar to that described above in connection with thecircuit of FIG. 1, the externally designated flash signal coupledthrough diode D3 disables the protection device when operating from aremote flash circuit. The flash signal causes transistor Q1 to conducton the occurrence of each flash to discharge capacitor C1 duringintervals sufiiciently closely spaced to prevent a potential to developacross that capacitor sufficient to render diod D9 conductive.

While the specific embodiments described employ specific logic asexamples, it is within the principles of the invention to employdifferent logic. Numerous other mod ifications of, uses of anddepartures from the specific embodiment described herein will beapparent to those skilled in the art without departing from theinventive concepts. Consequently, the invention is to be construed aslimited solely by the spirit and scope of the appended claims.

What is claimed is:

1. Traffic control apparatus responsive to signal control failure forproducing a cautioning control signal comprising:

a source of a cautioning signal,

a source of a first set of control signals directing traffic along afirst direction and a second set of control signals directing trafiicalong a second direction that intersects with said first direction,

an output semiconductor device coupled to said cautioning signal sourceand capable of assuming a first state and a second state which secondstate activates said cautioning signal source,

first and second semiconductor timing circuits coupled to said source ofcontrol signals and responsive to normal operation of said first set ofcontrol signals and said second set of control signals for continuouslyproviding said output semiconductor device with a disabling signal thatnormally maintains said output semiconductor device in said first statewhen both said first set of control signals and said second set ofcontrol signals occur in normal sequence,

said first and second timing circuits being responsive to the abnormaloccurrence of said first set of control signals and said second set ofcontrol signals respectively by providing an enabling signal to saidoutput semiconductor device to change the lattter device to said secondstate and thereby activate said source of a cautioning signal.

2. Traffic control apparatus in accordane with claim 1 and furthercomprising:

power supply means including means for rectifying A-C energy of powerline frequency for providing rectified impulses, and

means for applying said rectified impulses to said timing circuits andsaid output semiconductor device.

3. Trafiic control apparatus in accordance with claim 2 wherein saidfirst and second timing circuits include first and second timingsemiconductor devices respectively,

the occurrence of current flow in each of said devices being onlycontemporaneously with the occurrence of respective ones of saidrectified impulses.

4. Trafiic control apparatus in accordance with claim 3 wherein saidoutput semiconductor device comprises a unijunction transistor and saidfirst and second semiconductor timing circuits comprise first and secondtiming capacitors respectively, and further comprising:

means for charging said first and second capacitors,

first and second timing resistances connected to said first and secondtiming capacitors respectively,

means including said first and second timing resistances respectivelyfor charging said first and second capacitors with respective ones ofsaid impulses,

means including said first and second timing semiconductor devices forrespectively providing first and second respective discharge paths forsaid first and second capacitors, and

means including said output semiconductor device for providing anotherdischarge path for said first and second capacitors when the potentialon said capacitors exceeds a predetermined value to only then rendersaid output device conductive and in said second state.

5. Trafiic control apparatus in accordance with claim 4 wherein saidfirst set of control signals include a first directing signal and saidsecond set of control signals include a second directing signal,

means for deriving a first directing set of said rectified impulses fromsaid first directing signal,

means for deriving a second directing set of said rectified impulsesfrom said second directing signal,

means for coupling said first directing set to said first timingsemiconductor device to normally maintain the potential on said firsttiming capacitor less than said predetermined value,

means for coupling said second directing set to said second timingsemiconductor device to normally maintain the potential on said secondtiming capacitor less than said predetermined value,

whereby the absence of either of said first and second sets for a timeinterval greater than a predetermined period related to first and secondcharge time constants related to the product of each of said timingcapacitors and each of said timing resistances results in saidpredetermined value being exceeded and said output semiconductor devicerendered conductive.

6. Trafiic control apparatus in accordance with'claim 5 and furthercomprising:

a cautioning signal selection terminal,

switching means responsive to said output semi-conductor device being insaid first state for coupling said cautioning signal selection terminalto said source of a cautioning signal whereby the presence of acautioning signal selection signal on said cautioning signal selectionterminal activates said cautioning signal source, and

timing circuit inhibiting means responsive to the presence of saidcautioning signal selection signal on said cautioning signal selectionterminal for coupling ones of said rectified impulses to both said firstand second timing semiconductor devices to then maintain the potentialon said first and second timing capacitors less than said predeterminedvalue.

7. Trafiic control apparatus in accordance with claim 6 and furthercomprising at least a first phase input terminal, and

means for coupling said first phase input terminal to one of said timingcircuit semiconductor devices to selectively provide ones of saidrectified impulses to said one timing circuit semiconductor device.

8. Traffic control apparatus in accordance with claim 7 and furthercomprising a second phase input terminal, and

means for coupling said second phase input terminal to the other of saidtiming circuit semiconductor devices to selectively provide ones of saidrectified impulses to said other timing circuit semiconductor device.

9. Trafiic control apparatus in accordance with claim 2 wherein saidfirst and second timing circuits include first and second timingsemiconductor devices respectively,

means for establishing said first semiconductor device normallyconducting,

means for establishing said second semiconductor device normallyconducting, and

means responsive to selected ones of said rectified impulses forselectively rendering said first semiconductor device conducting andsaid second semiconductor device nonconducting, the occurrence ofcurrent flow in said first semiconductor device and the absence ofcurrent flow in said second semiconductor device being onlycontemporaneously with the occurrence of respective ones of saidrectified impulses. 10. Traific control apparatus in accordance withclaim 9 wherein said output semiconductor device comprises a unijunctiontransistor and said first and second timing circuits comprise first andsecond timing capacitors respectively, and further comprising:

means for charging said first and second capacitors, first and secondtiming resistances connected to said first and second timing capacitorsrespectively,

means including said first and second timing resistances respectivelyfor charging said first and second capacitors with respective ones ofsaid impulses,

means including said first and second timing semiconductor devices forrespectively providing first and second respective discharge paths forsaid first and second capacitors, and

means including said output semiconductor device for providing anotherdischarge path for said first and second capacitors when the potentialon said capacitors exceeds a predetermined value to only then rendersaid output device conductive and in said second state.

11. Traffic control apparatus in accordance with claim 10 wherein saidfirst set of control signals include a first directing signal and saidsecond set of control signals include a second directing signal,

means for deriving a first directing set of said rectified impulses fromsaid first directing signal, means for deriving a second directing setof said rectified impulses from said second directing signal,

means for coupling said first directing set to said first timingsemiconductor device to normally maintain the potential on said firsttiming capacitor less than said predetermined value, means for couplingsaid second directing set to said second timing semiconductor device tonormally maintain the potential on said second timing capacitor lessthan said predetermined value except when the duration of said seconddirecting signal exceeds a predetermined duration,

whereby the absence of said first set for a time interval greater than apredetermined first period related to a first charge time constantrelated to the product of said first timing capacitor and said firsttiming resistance and the presence of said second set for a timeinterval greater than a predetermined second period related to a secondcharge time constant related to the product of said second timingcapacitor and said second timing resistance results in saidpredetermined value being exceeded and said output semiconductor devicerendered conductive.

12. Traffic control apparatus in accordance with claim 11 and furthercomprising:

a cautioning signal selection terminal,

switching means responsive to said output semiconductor device being insaid first state for coupling said cautioning signal selection terminalto said source of a cautioning signal whereby the presence of acautioning signal selection signal on said cautioning signal selectionterminal activates said cautioning signal source, and

timing circuit inhibiting means responsive to the presence of saidcautioning signal selection signal on said cautioning signal selectionterminal for coupling ones of said rectified impulses to said firsttiming semiconductor device to then maintain the potential on said firsttiming capacitor less than said predetermined value.

13. Traffic control apparatus in accordance with claim 12 and furthercomprising at least a first phase input terminal, and

means for coupling said first phase input terminal to said first timingcircuit semiconductor device to selectively provide ones of saidrectified impulses to said first timing semiconductor device.

14. Traffic control apparatus in accordance with claim 13 wherein saidfirst phase input terminal bears a signal for rectification to providesaid rectified impulses only when said first directing signal occurssignalling traflic in a preferred direction to go and the latter signalfor rectification-is absent upon demand for occurrence of a demand for asignal that signals tratfic in said preferred direction to stop.

No references cited.

THOMAS B. HABECKER, Primary Examiner.

1. TRAFFIC CONTROL APPARATUS RESPONSIVE TO SIGNAL CONTROL FAILUREA FORPRODUCING A CAUTIONING CONTROL SIGNAL COMPRISING: A SOURCE OF ACAUTIONING SIGNAL, A SOURCE OF A FIRST SET OF CONTROL SIGNALS DIRECTINGTRAFFIC ALONG A FIRST DIRECTION AND A SECOND SET OF CONTROL SIGNALSDIRECTING TRAFFIC ALONG A SECOND DIRECTION THAT INTERSECTS WITH SAIDFIRST DIRECTION, AN OUTPUT SEMICONDUCTOR DEVICE COUPLED TO SAIDCAUTIONING SIGNAL SOURCE AND CAPABLE OF ASSUMING A FIRST STATE AND ASECOND STATE WHICH SECOND STATE ACTIVATES SAID CAUTIONING SIGNAL SOURCE,FIRST AND SECOND SEMICONDUCTOR TIMING CIRCUITS COUPLED TO SAID SOURCE OFCONTROL SIGNALS AND RESPONSIVE TO NORMAL OPERATION OF SAID FIRST SET OFCONTROL SIGNALS AND SAID SECOND SET OF CONTROL SIGNALS FOR CONTINUOUSLYPROVIDING SAID OUTPUT SEMICONDUCTOR DEVICE WITH A DISABLING SIGNAL THATNORMALLY MAINTAINS SAID OUTPUT SEMICONDUCTOR DEVICE IN SAID FIRST STATEWHEN BOTH SAID FIRST SET OF CONTROL SIGNALS AND SAID SECOND SET OFCONTROL SIGNALS OCCUR IN NORMAL SEQUENCE, SAID FIRST AND SECOND TIMINGCIRCUITS BEING RESPONSIVE TO THE ABNORMAL OCCURRENCE OF SAID FIRST SETOF CONTROL SIGNALS AND SAID SECOND SET OF CONTROL SIGNALS RESPECTIVELYBY PROVIDING AN ENABLING SIGNAL TO SAID OUTPUT SEMICONDUCTOR DEVICE TOCHANGE THE LATTER DEVICE TO SAID SECOND STATE AND THEREBY ACTIVATE SAIDSOURCE OF A CAUTIONING SIGNAL.